The present application relates to disc brake assemblies having a tone ring connected thereto or otherwise associated therewith and methods for forming disc brake assemblies with tone rings.
Modern vehicles may employ an anti-lock braking system (“ABS system”) to increase the traction and control of the vehicle during adverse driving conditions. ABS systems prevent the wheels from locking by rapidly releasing and reapplying brake pressure. A typical ABS system includes speed sensors for monitoring the rotational speed and/or acceleration of each wheel of the vehicle relative to the other wheels of the vehicle. The ABS system may be actuated when the rotational speed or acceleration of one or more wheels is different than the rotational speed or acceleration of the other wheels.
Speed sensors may measure the rotational speed of a wheel by monitoring the rotation of the associated brake rotor. In particular, a brake rotor may be provided with an associated tone ring having a plurality of exciter teeth thereon. A sensor may be positioned adjacent to the tone ring to detect the change in magnetic flux caused by movement of the exciter teeth relative to the sensor.
Prior art attempts to integrate tone rings with brake rotors have presented numerous problems and disadvantages. For example, brake rotors with cast-in exciter teeth have presented integrity issues due to the difficulty of obtaining tight tolerances using a foundry casting process, as well as corrosion breakdown of the exciter teeth. Furthermore, cast-in teeth require the application of an expensive rust preventative coating. Bolt-on tone rings require tapped holes in the brake rotor, fastening ears on the tone ring and fasteners for securing the tone ring to the brake rotor, thereby increasing costs and presenting reliability issues. Finally, press-fit tone rings are subject to failure due to the use of different materials for the tone ring and the brake rotor, wherein the different materials may expand differently under thermal conditions, thereby causing detachment of the tone ring from the brake rotor.
Accordingly, there is a need for a new and improved disc brake assembly having a tone ring connected thereto.